Based on interviews with 48 former detainees and 37 others including policy analysts, activists, former military, security, and intelligence personnel and family members of people detained by South Sudan’s National Security Service between 2014 and 2020, this HRW report documents serious human rights violations by the NSS in South Sudan, including torture and other ill-treatment of detainees, arbitrary arrests, unlawful detentions, unlawful killings, enforced disappearances, forced returns and violations of privacy rights.